The invention relates to methods and apparatus for the automatic testing of electrical and electronic circuitry. More specifically, it relates to the testing of logic circuits. For example, the methods and apparatus to be more specifically described can be used for applying test signals to a logic circuit and to determine, from the resultant outputs produced by the circuit, whether the circuit is operating correctly and, if not, which part is faulty. The logic circuits to be tested may be in integrated circuit form.
The invention applies not only to "in-circuit" testing of individual logic circuits of a circuit board but also to the testing of a complete board or part of a board via its edge connections.